The present invention relates to a method and a device for forming contact between a control unit and current loads of internal combustion engines.
German Published Patent Application No. 42 25 329 describes a device for forming contact between a control unit and actuators of an electromagnetic valve controller. The internal combustion engine has a cylinder head in which gas exchange valves, which are activated by the electromagnetic actuators, are arranged, the cylinder head being covered by a cylinder head cover. The actuators include opening and closing magnets which are actuated by the control unit. For this purpose, each actuator has a cable which extends from the respective actuator within the cylinder head cover to a recess in the cylinder head cover through which the cable is subsequently plugged in order to be connected to the control unit.
A significant disadvantage of the device is the complex mounting of the internal combustion engine because the cables must be extended individually to the recess in the cylinder head. Moreover, when the cylinder head cover is fitted on, the cables which are loosely guided in the cylinder head cover can be squashed.
German Published Patent Application No. 198 54 542 also describes a device for forming contact between a control unit and actuators of an electromagnetic valve controller. The internal combustion engine has a cylinder head which is composed of three housing components, the actual cylinder head, a frame part which is connected with flanges to the cylinder head and a cylinder cover which can be fitted onto the frame part. The formation of contact between the control unit and the actuators is made by electrical components through the frame part, the electrical components being at least partially integrated into the frame part.
It is an object of the present invention to reduce the mounting effort incurred in forming contact between a control unit and current loads of an internal combustion engine, to simplify the mounting operations generally, and to reduce as much as possible the installation space required.
The above and other beneficial objects of the present invention are achieved by providing a method and a device as described herein.
A significant advantage of the present invention is the optimization of the mounting operations. The electrical components or contact-forming housings which are required for the formation of contact between the control unit and the current loads of the internal combustion engine are in respectively predefined positions during the entire mounting operation, i.e., the electrical components of the current loads or the contact-forming housings merely have to be moved during the mounting from a predefined prefixed position on the current load into a predefined fixed position indirectly or directly in the cylinder head cover, after which it is possible to form contact between the current loads and the control unit in the fixed position without difficulty.
Control units and in particular valve control units are appropriately attached to the cylinder head cover. The formation of contact between the control unit, spanning the entire cylinder bank, and the current loads is subject to large tolerances. The floating fixing of the contact-forming housing in the cylinder head cover or in an intermediate frame which is supported in the cylinder head cover therefore permits virtually all the tolerances which originate from the current loads or the mounting thereof on the cylinder head to be equalized, as a result of which subsequent processing of the mounting components in order to reduce tolerances is no longer necessary.
The use of the intermediate frame permits further reduction of the tolerances by group-formation of the contact-forming housings in that a long tolerance chain is split up into a plurality of small tolerance chains. The actual formation of contact between the contact-forming housing and the control unit is made easier by a receptacle in the intermediate frame into which the control unit is latched and may then be pivoted in this receptacle onto the contact-forming housing or guided into the contact-forming housings, which results in an additional reduction in the tolerances and to a reduction in the contact-forming forces.
While the internal combustion engine is operating, the actuators are subjected to extreme vibration loading, which may result in functional faults if the contact-forming housings were connected directly to the actuators. By virtue of the fact that the contact-forming housings are connected to the actuators via leads or cables and do not have any direct contact with the actuators, there is a decoupling between the actuator and contact-forming housing, permitting the latter to function in an undisrupted way.